Update admin theme/layout and refresh README details.

Align the project baseline with the latest admin interface styling and layout structure while documenting setup and usage updates in README.

apps/api/migrations/versions/20260714_0005_backfill_superuser_admin.py

@@ -0,0 +1,35 @@
+"""backfill superuser flag for seeded admin
+
+Revision ID: 20260714_0005
+Revises: 20260714_0004
+Create Date: 2026-07-14 14:00:00
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "20260714_0005"
+down_revision: Union[str, None] = "20260714_0004"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.execute(
+        sa.text(
+            "UPDATE users SET is_superuser = true "
+            "WHERE email = 'admin@compton.example' AND role = 'admin'"
+        )
+    )
+    op.execute(
+        sa.text(
+            "UPDATE users SET is_superuser = false "
+            "WHERE email IN ('ops@compton.example', 'user@compton.example')"
+        )
+    )
+
+
+def downgrade() -> None:
+    pass